LAUREL, Miss. — Chris McDaniel’s Republican campaign for the Senate barreled through Mississippi on Sunday on anti-establishment, Tea Party-invigorated energy as the state’s runoff primary race entered its final hours.

The Tea Party Express, one of the nation’s largest organizations aligned with the movement, was the host of three bus tour events earlier this weekend, with a fourth planned for later Sunday — all intended to raise support for Mr. McDaniel, who will face the incumbent, Senator Thad Cochran, in the runoff election on Tuesday.

Five years have passed since Tea Party groups began protesting big government at summer town-hall meetings across the country, and this runoff has become a test of the movement’s durability, especially after a Tea Party challenger defeated the House majority leader, Eric Cantor, in a primary this month.

At the tour’s kickoff event on Friday evening in a parking lot here, 10 minutes from Mr. McDaniel’s hometown, American flags waved as a husband-and-wife band, the Rivoli Revue, jammed on guitars bearing American flag insignia and sang songs criticizing government overreach with titles like “Restoring America,” “USSA” and “Repeal Obamacare.”

“The establishment has ‘fell’ my friend. Thad Cochran has to go,” the couple sang for 70 Mississippians from a stage at the side of a Ramada Inn. Behind the band hung a “Don’t Tread on Me” flag. “Those bailouts have to stop,” went another song. “That stimulus must end. Repeal Obama health care. No cap-and-trade my friend.”

Susan Barnett, a former teacher who has known Mr. McDaniel since he was a toddler, exhorted the crowd: “Who is going to elect our nominee? Let’s not let it be the special-interest lobbyists.

“They’re not going to select our senatorial candidate. We the people will select him. It will not be the political machine and the Republican old guard.”

The crowd cheered as Ms. Barnett and each of the roughly one dozen speakers, including the talk radio host Lars Larson, railed against the nation’s capital or against Mr. Cochran. In a county where Mr. McDaniel won 85 percent of the vote in the June 3 race that led to the runoff scheduled for Tuesday, any attack on his opponent — personal or political — was sure to draw boisterous applause and hollering.

This race has been described as featuring more mudslinging than any in this election cycle. On the stump, Mr. McDaniel is far more polite, taking pains to note how he respects Mr. Cochran’s record. Then he attacks it.

“Senator Cochran has been there for 42 years, and no one can name a single fight that he’s led for the conservative movement,” Mr. McDaniel said at an event in Madison, a wealthy suburb of Jackson, on Thursday night with former Senator Rick Santorum of Pennsylvania. “He wants to scare you into voting for the status quo.”

Mr. McDaniel accompanied the Tea Party Express bus on its Saturday stop to Tupelo, and he was scheduled to ride with it to Biloxi on Sunday for an event hours before Mr. Cochran was to host Senator John McCain, Republican of Arizona, a few miles away in Gulfport.

For as much as the campaign has been portrayed as a battle between the Tea Party and the establishment, both candidates were relying on established star power as they made their closing arguments. Mr. Cochran’s events with Mr. McCain on Sunday in Biloxi and Monday in Jackson are his campaign’s largest ending rallies, and the Chamber of Commerce was broadcasting a television advertisement supporting the incumbent that featured the former Green Bay Packer quarterback Brett Favre, a Mississippi native.

Mr. McDaniel brought Mr. Santorum, who spent 16 years in Washington, to Mississippi on Thursday, and the candidate has benefited from television ads broadcast during time paid for by the Club for Growth, a political advocacy group based in Washington.

Val Root, a Florida Tea Party activist who teaches gifted elementary students, traveled to Mississippi with her husband to campaign for Mr. McDaniel and to distribute the American Patriot News, a newsletter they produce.

“I think Washington is a beautiful city, but it’s one of the more corrupt places you could ever think of,” Ms. Root said. “When we send good candidates up there, it only takes two or three weeks before they fall into step.”

When asked how she could be certain Mr. McDaniel would not follow the same path if elected, she said she could not. But then she added, “Well, I think we have to trust some people.”